Water dispersible compositions containing natural hydrophilic water-insoluble pigments, methods of preparing same and their use

ABSTRACT

Ready-to-use water dispersible pigment compositions containing waer-insoluble, hydrophilic pigments are provided. The compositions comprise a stable dispersion of the pigment such as a porphyrin pigment, carmine, curcumin and a carotenoid in the form of bodies of an average size which is at the most 10 mum is provided. The pigment bodies are dispersed without the use of a surface active substance in an aqueous phase comprising a hydrocolloid. The natural pigment compositions which are useful for coloring of food products and pharmaceuticals do not migrate in the products and they are acid stable. The compositions are useful in coating compositions for tablets and dragees.

This is a Continuation Application of Application No. 09/101,764, filedSep. 21, 1998 , now abandoned, which is the U.S. national stage ofPCT/DK97/0026, filed Jan. 20, 1997.

FIELD OF INVENTION

The present invention provides ready-to-use water dispersiblecompositions containing natural hydrophilic, water-insoluble pigmentswhich are useful for the colouring of edible products and pharmaceuticalproducts.

TECHNICAL BACKGROUND AND PRIOR ART

Colouring agents are commonly used as additives in the manufacturing offood products and pharmaceuticals. A wide range of such colouring agentsare commercially available making it possible, when a particular colourtone is desired, to select a single agent having the desired colour or amixture of agents which in an appropriate combination impart the desiredcolour to the product.

The commercial colouring agents can be synthetic substances which arealso normally referred to as dyes or azodyes, or the agents can bepigments of natural origin, e.g. in the form of plant materialcontaining the pigment or as more or less purified pigments extractedfrom plants, animals or microorganisms.

Occasionally, food grade or pharmaceutically acceptable colouring agentsare provided in the form of synthetic or artificial substances havingthe same chemical composition as naturally occurring pigments. This typeof colouring agents are also referred to in the art as “natureidentical” colours. However, in the present context the term “naturalpigment” is used exclusively to designate pigments which are derivedfrom a natural source.

Food grade or pharmaceutically acceptable natural pigments can be watersoluble or they can be essentially water-insoluble or sparingly solublein water, including hydrophobic pigments. A water soluble naturalpigment as such can only be used for colouring a product having anaqueous phase during and/or after manufacturing. Similarly, the use of ahydrophobic natural pigment as such requires that the product to becoloured has a lipid phase in which the pigment is soluble.

Certain pigments of natural origin such as metal chelates of carminicacid and curcumin, norbixin and chlorophyllin are insoluble in water atneutral pH or below but soluble in alkaline solutions. In this context,the term “natural hydrophilic water-insoluble pigment”, refers topigments of natural origin which are generally insoluble in aqueousmedia at about neutral pH or below but soluble in aqueous media at pHvalues in the alkaline range. Accordingly, the natural hydrophilicwater-insoluble pigments which are dissolved in alkaline mediaprecipitate at a pH level below 7.

However, it may be desirable to obtain the colour tone of a particularwater-insoluble, hydrophilic natural pigment or a mixture of suchpigments in a food product or a pharmaceutical product which does notcomprise a phase in which the pigment is readily soluble, e.g. anaqueous phase with a pH value below 7. There is therefore an industrialneed for colouring agents containing water-insoluble, hydrophilicnatural pigments in the form of acid-proof water-miscible or waterdispersible compositions.

Commercial water dispersible preparations of water-insoluble naturalpigments such as carmine are e.g. available from Overseal Foods Ltd,Derbyshire, England under the trade name miChroma™. These products areprovided as suspensions in propylene glycol and glucose syrup and themanufacturer states in data sheets that the products will stain clothingand skin.

In the pharmaceutical industry and the food industry colouring agentsare used widely for the colouring of sugar coatings of e.g. sugarconfectionaries, dragees, tablets, pills, gums and granulates.Presently, most colouring agents available for this purpose are based onsynthetic dyes, e.g. in the form of food grade lakes which are pigmentsformed by precipitation and absorption of a dye on an insoluble base orsubstrate, such as alumina hydrate. A wide range of coating compositionscomprising such lakes are available. Presently, propylene glycol-baseddispersions are commonly used to incorporate such dyes into solutionsused for film-coating of pharmaceutical tablets. It is recognized in theart that propylene glycol has a negative effect on both the processingtime and physical properties of the film.

WO 92/11002 discloses a film-forming composition for use in coatingtablets and capsules, consisting of powdered pigment particles, afilm-forming, water soluble or water dispersible, edible polymer andabout 1-30% by weight of water. This composition is described as a wetpowder blend and it is manufactured by blending the dry ingredientfollowed by the addition of water by spraying it onto the blend.

A well-known problem associated with the use of water soluble ordispersible compositions of colouring agents is the tendency of suchagents to migrate from one compartment of a food product or apharmaceutical product to another where the colouring is undesired. Thisphenomenon is also referred to as “bleeding”.

It is therefore particularly desirable to have water soluble ordispersible natural pigment preparations which do not migrate duringmanufacturing or within the finished product during storage andhandling, or come off when handled.

Other problems or shortages associated with known water-miscible orwater dispersible natural colouring agents are low stability againstlight, heating, catalyst and oxygen generated changes of the colour hueand an unsatisfactory covering ability when used for coating purposes.Problems which are frequently encountered with known water dispersiblecompositions comprising hydrophilic, water-insoluble pigments when usingsuch compositions in acidic media are that the pigments precipitate,separate and accumulate on surfaces and/or change their colour hue.

Thus, it is apparent that water dispersible colouring compositionscontaining water-insoluble, hydrophilic natural pigments, which arebased on aqueous dispersions of the pigment without potentiallyundesirable additives including surface active substances or propyleneglycol, which are suitable for manufacturing of food products as well aspharmaceutical products, which are more stable to degradation, which donot migrate and which are not associated with the above problems havehitherto not been available to the industry.

The advantages obtained with the colouring agents of the presentinvention in non-powdered form include:

their use give no dusting problems as it is the case with powderedproducts,

in contrast to a powder product they are more readily dispersible inaqueous systems,

their manufacturing does not include a drying step which implies thatthe production costs are lower and that the pigments are not damaged byheat and oxygen,

they possess increased dosage performance,

they can be provided with a water content and a consistency which isadapted to the particular field of use, e.g. ranging from concentratedpastes to low viscosity products.

In general, the advantages of the compositions according to theinvention include:

they do not give rise to migration problems,

they do not contain undesirable additives,

they do not precipitate, separate and accumulate on surfaces and/orchange their colour hue at low pH, i.e. they are what is referred to inthe art as “acid-proof”

they make it possible to confer a desired cloudiness or reflection tootherwise clear media in a controlled manner.

SUMMARY OF THE INVENTION

Accordingly, the invention pertains in one aspect to a ready-to-usepigment composition comprising a dispersion of a water-insoluble,hydrophilic natural pigment in the form of bodies of an average sizewhich is at the most 10 μm, said bodies being dispersed in the absenceof a surface active substance in an aqueous phase comprising ahydrocolloid, the composition containing at least 5% by weight of water.

In another aspect the invention provides a ready-to-use waterdispersible pigment composition comprising a dispersion of awater-insoluble, hydrophilic natural pigment in the form of bodies of anaverage size which is at the most 10 μm, said bodies being dispersed inthe absence of a surface active substance in an aqueous phase comprisinga hydrocolloid, the composition containing less than 5% by weight ofwater, subject to the limitation that when the pigment is carmine orspray dried norbixin the hydrocolloid is not gelatin.

In further aspects the invention relates to the use of such acomposition in the manufacturing of an edible product whereby thecomposition is dispersed in the aqueous phase of said food product,including the use in food products wherein the aqueous phase has a pHwhich is at the most 7, and the use of the above compositions in themanufacturing of an edible product comprising multiple, separatedcompartments whereby the composition is dispersed in one or moreselected compartments, the composition in one compartment essentiallynot migrating to other compartment.

In a still further aspect, the invention relates to the use of the abovecompositions in the manufacturing of a pharmaceutical product.

Still further objectives of the invention are to provide an edibleproduct or a pharmaceutical product comprising the above compositions.

The invention also provides a first method of preparing a ready-to-usewater dispersible pigment composition, said method comprising preparinga dispersion of a water-in-soluble, hydrophilic natural pigment bymixing the pigment in the absence of a surface active substance into anaqueous phase containing a hydrocolloid, to obtain a dispersioncontaining the pigment in the form of bodies having an average size ofat the most 10 μm, the composition containing at least 5% by weight ofwater.

In another aspect the invention pertains to a first alternative methodof preparing a ready-to-use water dispersible pigment composition, saidmethod comprising the steps of preparing an alkaline aqueous solutioncomprising a water-in-soluble, hydrophilic natural pigment, preparing anaqueous dispersion or solution of a hydrocolloid, and mixing thealkaline aqueous solution with the aqueous dispersion of a hydrocolloid,and if desired, adjusting the pH to a level which causes the pigment toprecipitate, to obtain the composition comprising the pigment in theform of bodies having an average size of at the most 10 μm, thecomposition containing at least 5% by weight of water.

In yet another aspect the invention relates to a second alternativemethod of preparing a ready-to-use water dispersible pigmentcomposition, said method comprising the steps of preparing an alkalineaqueous solution comprising a water-insoluble, hydrophilic naturalpigment followed by decreasing the pH to a level which causes thepigment to precipitate, resulting in a dispersion of precipitatedpigment, preparing an aqueous dispersion or solution of a hydrocolloidand mixing the dispersion comprising the precipitated pigment with thedispersion or solution of hydrocolloid to obtain the compositioncomprising the pigment in the form of bodies having an average size ofat the most 10 μm, the composition containing at least 5% by weight ofwater.

DETAILED DISCLOSURE OF THE INVENTION

The ready-to-use compositions according to the invention comprise or arebased upon a dispersion of a water-insoluble, hydrophilic naturalpigment. As used herein the term “water-insoluble, hydrophilic”indicates that the pigment in the amounts used herein is water-insolubleor sparingly soluble in aqueous media at about neutral pH or below or atpH levels up till about 9, but soluble in an alkaline aqueous mediumsuch that the pigment will occur as a separate phase in aqueous media atneutral pH or below.

In this context, the term “surface active substance” is usedinterchangeably with the term “surfactant” and “tenside” and it includescompounds which are generally referred to as anionic, cationic,non-ionic, amphoteric and zwitterionic surfactants. A review of suchsurface active substances is e.g. given by I Smith, Blackie Academic &Professional, 1991, 169-201. As used herein the term “surface activesubstance” does not include hydrocolloids as mentioned below. It is tobe understood, that the expression “in the absence of a surface activesubstance” does not exclude the presence of a surfactant in minoramounts which substantially does not impart surface activity.

The natural pigment can be any food grade or pharmaceutically acceptablewater-insoluble, hydrophilic colouring matter derived from a naturalsource. Thus, the pigment may either be in a substantially pure form orit may be contained in the material where it occurs naturally such as aplant or animal material, optionally in combination with a food gradeand/or pharmaceutically acceptable carrier. The most widely used naturalpigments as defined herein include water-insoluble, hydrophiliccarotenoids such as e.g. norbixin, curcumin, porphyrin pigmentsincluding chlorophyllin, and carmine.

Carotenoids which have yellow, orange or red colours occurs widely innature and important sources are plants including grasses, the annattotree, citrus species, Capsicum annum, Crocus sativus flowers andmarigold flowers, marine algae, yeast and some animals. Carotenoids orderivatives hereof which are water-insoluble and hydrophilic are usefulin the present invention.

A further important class of natural pigments is quininoid pigments ofwhich the most widely used is cochineal carmine which is obtained byaqueous extraction from the insect Coccus cacti. Normally, the extractis precipitated as the insoluble aluminium lake known as cochinealcarmine which is soluble in alkaline aqueous media but sparingly solublein aqueous media having pH below about 9.

Further water-insoluble, hydrophilic natural pigments that are useful inthe present invention are curcumin, which is the major pigment inturmeric, the coloured oleoresin extract of the Curcuma plant, andwater-insoluble hydrophilic porphyrin pigments such as chlorophyllin andpigment based substantially on water soluble salts of derivatives ofphaeophytin a or b.

In accordance with the invention the natural pigments in the abovecompositions are present in the form of bodies of an average size whichis at the most 10 μm. Preferably, the pigment is in the form of bodieshaving an average size of at the most 5 μm, preferably at the most 2 μmand more preferably at the most 1 μm, e.g. at the most 0.1 μm or at themost 0.01 μm. It is contemplated that the ability of the pigment toprovide an attractive colour hue and to provide an effective colouringe.g. when the composition is used in coating compositions, is increasingwith decreasing size of the pigment bodies. The colour intensity, colourhue and the transparency can be controlled by appropriately selectingthe size of the bodies.

In accordance with the invention, the pigment bodies are preferablysolid particles such as e.g. solid particles of curcumin, carmine,norbixin and chlorophyllin.

As mentioned above, the natural pigment-containing bodies are dispersedin an aqueous phase comprising a hydrocolloid and the dispersion isprovided without the addition of surface active substances such as anemulsifying agent or a surfactant. For the purposes of the presentinvention suitable hydrocolloids include: an animal or vegetable proteinsuch as gelatin which can be derived from mammals or fish, milk proteinor soy protein, an exudate such as gum arabic, tragacanth and other gumssuch as guar gum, locust bean gum or xanthan gum, agar, alginate,carrageenan, furcelleran, pectin, cereal flours and starches, starchderivatives, microcrystalline cellulose, cellulose derivatives such ascarboxymethyl cellulose, dextran, and synthetic hydrocolloids includingas an example polyvinylpyrrolidone. Presently preferred hydrocolloidsare gelatin and gum arabic. The hydrocolloid can also be a mixture ofhydrocolloids.

It is contemplated that the hydrocolloid acts as a protective colloid,that it prevents agglomeration of the pigment bodies and that itprovides wetting and dispersing activity.

The hydrocolloid is suitably used in an amount in the range of 1-90% byweight of the natural pigment, such as in the range of 2-80% by weight.In preferred embodiments, the amount of hydrocolloid is in the range of3-60% by weight such as in the range of 5-50% by weight and e.g theamount of hydrocolloid can be less than 10% by weight of the naturalpigment. In other preferred embodiments, the amount of hydrocolloid ismore than 100% by weight of the natural pigment, i.e. the ratio betweenpigment and hydrocolloid can be in the range of 1:1 to 1:10000, such asin the range-of 1:10 to 1:5000 or in the range of 1:100 to 1:1000.

The amount of pigment may also be calculated on the composition. Thus,the amount of hydrocolloid is preferably in the range of 1-50% by weightof the composition, preferably in the range of 5-40% by weight, such asin the range of 10-25% by weight.

In accordance with the invention, the composition may preferably containat least 5% by weight of water such as in excess of 10% by weight. Oneadvantage of such a composition is the possibility of providing it witha water content within a wide range whereby the composition can beadapted to particular customer demands. A composition containing atleast 5% by weight of water having a low content of water will appear asa powder or a viscous paste. Depending on the natural pigment, acomposition having a water content in the range of 5-40% by weight willtypically appear as a powder, a paste, a gel or a viscous liquid. Withan increasing water content above this level, the consistency of thecomposition will acquire an increasingly lower viscosity and becomeliquid. It is contemplated that a concentrated pasty composition will beadvantageous from a user point of view, since it can easily betransported and stored and furthermore, the natural pigment will beprotected well against light and oxidation in such a concentrate. It isevident that a concentrated composition according to the invention withan initial water content of at least 5% by weight can be diluted withwater to any desired pigment concentration.

In other useful embodiments of the invention the above compositionscontain less than 5% by weight of water, subject to the limitation thatwhen the pigment is carmine or spray dried norbixin the hydrocolloid isnot gelatin.

The selection of a suitable amount of the natural pigment in thecomposition according to the invention depends on the particular type ofpigment and the particular intended application for the composition anda wide range of the amount of pigment is therefore contemplated such asa range of 0.5-90% by weight of the dispersion, although amounts inexcess of this range is envisaged. In preferred embodiments, the amountof pigment is in the range of 1-50% by weight, and may more preferablybe in the range of 5-40% by weight. Based on the dispersed phase auseful amount is in the range of 10 to 30% by weight, including about20% by weight of the dispersion.

In specific embodiments of the invention the pigment is in the form ofpigment particles obtained by precipitation caused by acidification ofan alkaline solution of the pigment.

In accordance with the invention, the aqueous phase of the compositioncan as a further component comprise a carbohydrate or a sugar alcohol ora mixture hereof. The carbohydrate is preferably selected from amonosaccharide, a disaccharide or an oligosaccharide including asexamples glucose, lactose, fructose, sucrose. The sugar alcohol can e.g.be selected from sorbitol, mannitol, dulcitol, adonitol or sorbitol. Theamount of the sugar alcohol is preferably in the range of 0-95% byweight of the dispersion, such as 5-50% by weight including the range of10-30% by weight.

In useful embodiments, the composition according to the invention is acoating composition comprising the above dispersion of awater-insoluble, hydrophilic natural pigment and at least one furtheringredient which is normally used in a composition for colouring coatinglayers of e.g. a tablet, a dragee, a pill or a capsule. Such furtheringredients can be selected from additional sugar to provide a syrup, aplasticizing agent such as propylene glycol, a film coating resin, astabilizing agent, a further colouring agent such as CaCO₃ or titaniumdioxide, or a lower alcohol. The composition may also be a compositionintended for decoration purposes such as a glazing composition or a“printing” composition.

The composition according to the invention is, as it is mentioned above,useful as a colouring agent for food products. Any food productcomprising an aqueous phase wherein the composition is dispersible canbe coloured. A large number of food products have an aqueous phase witha pH below 7 and this acidic environment will in many cases render apigment as such unstable and the pigment will tend to precipitateresulting in a change of the colour hue. This is e.g. observed inproducts such as acidified milk products. The compositions of thepresent invention are specifically useful in an acidic food productsince the compositions are acid-proof and do not precipitate.

In another useful embodiment of the invention the composition issuitable for colouring of liquid food products including soft drinks,carbonated beverage products and milk products.

An interesting application of the composition according to the inventionis the colouring of edible products being manufactured by extrusion,e.g. edible film for containing a food product such as a meat product. Atypical example hereof is collagen films used as casings for sausageproducts. An effective amount of the colouring composition is added tothe aqueous mixture to be extruded or casted and the resulting ediblefilm will contain the colour pigments. It has been found that thenatural pigments when incorporated in such extruded edible films incontrast to known food colours do not migrate into the contained foodproduct and furthermore, the pigment is not released into water in whichthe products are cooked.

Other examples of extruded products where the pigment compositionsaccording to the invention are useful include breakfast cereals, cakes,bread, snacks, confectionary products, breadings, crisps and grains. Ithas been found that the fact that the compositions do not contain anylipids or surface active substances make them particularly useful in themanufacturing of expanded products made by an extrusion process, sincethe expansion in such processes is lower when lipids and/or surfaceactive substances are added to the extrusion mixture.

A further advantageous use of the compositions is the colouring ofconfectionary products including as examples candies, acid drops andjelly products since the pigments in the compositions according to theinvention are acid stable.

Several food products such as e.g. soft drinks, juices, soups and saucesare manufactured as initially liquid products which are subsequentlydehydrated to a dry, storage stable product typically having a watercontent of at the most 10% by weight. The compositions according to theinvention are also useful for the colouring of such products in that thecolouring of the products after rehydration will substantially be of thesame strength and hue as the starting liquid food product.

As it is mentioned above, it is a well known problem in the foodindustry that colouring agents used in food products tend to migratewithin the food product or into the environment of the product. Thisphenomenon is also in the art referred to as “bleeding”. This problem isparticularly troublesome if it occurs in food products which comprisemultiple, separated compartments or layers where the colouring agent isnot added to all of such compartments, but only to one or more selectedcompartments. A colouring agent which do not migrate in such productsare therefore highly desirable in the industry. It has been found thatthe pigments of the compositions according to the invention are retainedin the compartment(s) to which they have been added and do not migrateinto adjacent non-coloured compartments.

One typical example of such a compartmentalized or layered food productis dessert products, which optionally are acidulated, comprising atleast one layer of fruit filling to which a colouring agent is added,and one or more layers of other ingredients also having an aqueous phasebut to which a colouring agent is not added. Another example of such aproduct is a layered cake. It is evident that migration of colouringagent into the non-coloured layers result in a highly unacceptableappearance of these layered products. As it is shown in the belowexamples, the compositions according to the invention can be used insuch products without giving rise to “bleeding” problems. A furtherexample of a product where it is advantageous to avoid migration ofpigments is a cereal breakfast product to be eaten with milk.

Avoidance of pigment migration is also critical in connection withedible products comprising a surface decoration layer in which acolouring agent is dispersed. Clearly, it is undesirable if the addedpigment migrates from the decoration layer into the subjacent productlayer. Typical examples of surface decorated products are meat productssuch as surimi and other delicatessen products where the decoration e.g.may be in the form of a water-based gel which is coloured with thepigment composition while liquid and subsequently applied on the productto solidify. Other examples of surface decorated products are bakeryproduct having sugar icing (glazing) on top or coloured decorationparticles. When added to such decoration layers or particles, thepigments in the compositions according to the invention do not migratefrom the layers or particles.

Dragees constitute a particular type of edible multilayered productswhere one or more coating layers typically consisting of sugar areapplied onto a center of an edible ingredient. Examples of such centersto be coated include chewing gum, sugar granulates, sugar tablets andchocolate. Colouring of such edible centers is typically carried out inone or more panning steps where the centers are coated with a sugarsyrup containing the colouring agent. Normally, it is required to applyseveral coating layers to obtain a sufficient covering with colour. Withknown water soluble or dispersible colouring agents based on lakes it isfrequently required to apply 20 coating layers or more. It has beenfound that the compositions according to the invention are highlysuitable for such coating purposes and that dragees with a sufficientcolouring can be obtained by applying less than 20 layers, such as 2-15layers. Furthermore, it has been found that the natural pigments of thecompositions as contained in coating layers do not come off on fingerson handling or on mucosal surfaces when the dragees are consumed.

A highly attractive characteristic of the compositions according to theinvention is that they are useful as colouring agents in themanufacturing of a pharmaceutical product. Thus, the compositions can beused for colouring of pharmaceutical products comprising multiple,separated compartments essentially in the same manner and with the sameadvantages as described above for compartmentalized food products. Inparticular, the compositions according to the invention are useful forcolouring of compositions for conventional film-coating of tablet, pillsor granules containing pharmaceutically active substances.

For such coating purposes the water dispersible composition according tothe invention is typically added to a sugar syrup suspension, e.g. usingsucrose. The solids content of such a coating syrup is normally in therange of 60-80% by weight. The amount of the natural pigment compositionwhich is added to the coating syrup is generally in the range of ½-50%by weight of the syrup. The thus coloured coating mixture may containfurther components such as stabilizers, preservatives, viscositymodifying agents and plasticizers.

The pharmaceutical centers are coated repeatedly in a conventionalpanning process and the number of repeated coatings required depends onthe particular pigment and the desired appearance of the finishedproduct. However, with the composition according to the invention,relatively few coating layers are required to obtain an attractivecolouring. Thus, less than 20 layers is normally required and in mostcases, 5-15 layers will suffice.

In addition to the above applications of the compositions, it iscontemplated that they are also useful for colouring of pharmaceuticalproducts in liquid form such as solutions, suspensions or dispersionhaving an aqueous phase.

As mentioned above, the present invention provides in one aspect a firstmethod of preparing the ready-to-use water dispersible pigmentcompositions according to the invention.

In a first step of this method a dispersion of a water-insolublehydrophilic natural pigment is prepared by mixing the pigment into anaqueous phase. This mixing step is carried out without the addition ofsurface active substances such as emulsifying compounds, but in thepresence of a hydrocolloid of a type and in amounts as mentioned above.As also mentioned above the invention pertains to a first and secondalternative method of preparing the ready-to-use water dispersiblepigment compositions according to the invention.

The mixing steps in the above methods can be carried out by anyconventional mixing or blending technique known in the art. Optionally,the mixing can be followed by comminution to obtain discrete pigmentbodies having a size of at the most 10 μm. However, it may beadvantageous to continue the comminution until the pigment is in theform of bodies having an average size of at the most 5 μm, preferably atthe most 2 μm and more preferably at the most 1 μm. It may also beadvantageous to let the comminution proceed until an average body sizeof at the most 0.1 μm such as at the most 0.01 μm is achieved

The above comminution step may be repeated one or more times in order toobtain the required body size.

Applicable comminution techniques include milling and homogenization asit is described in the below examples.

In useful embodiments of the invention the pigment is in the form ofparticles obtained by precipitation of the pigment caused by acidifyingan alkaline solution of the pigment.

In useful embodiments of the methods according to the invention, theamount of hydrocolloid is less than 10% by weight of the pigment.

The steps of dispersing the pigment can, if desired, be carried out inat least two steps in which an additional amount of hydrocolloid may beadded in the second and/or any subsequent step.

It will be understood that the methods of the invention may alsocomprise the preparation of a pigment dispersion in which a mixture oftwo or more water-insoluble, hydrophilic natural pigments is used. Inthis manner pigment compositions having a particular attractive colourtone can be provided as a result of the combination of two or morepigments having differing colours.

As also mentioned above, the methods may in accordance with theinvention comprise the addition of a carbohydrate to the aqueous phaseeither before or after the mixing or comminution or they may comprisethe incorporation into the dispersion of the water-insoluble,hydrophilic natural pigment of at least one further ingredient. Suchfurther ingredients may e.g. be selected from antioxidants, stabilizingagents, plasticizers, viscosity modifying agents, alcohols, resins andpreservative agents.

In useful embodiments of the invention the above methods comprise afurther step of drying to obtain a composition containing less than 5%by weight of water, subject to the limitation that when the pigment iscarmine or spray dried norbixin, the hydrocolloid is not gelatin.

The present invention is further illustrated by the followingnon-limiting examples:

EXAMPLE 1

Preparation of a Carmine Composition

7.9 kg gelatin (dry weight) was added slowly to 17.3 kg demineralisedwater at a temperature of about 65° C. with stirring until the gelatinhad dissolved. 14.2 kg of sucrose was added with agitation until thesugar was dissolved. 10.5 kg of carmine lake powder (50-52% carmine) wasadded to the above solution under agitation using a mechanical stirreruntil a homogeneous mixture was obtained.

The mixture was milled using a suitable equipment until a stable pigmentdispersion was obtained. The milled product was heated under gentleagitation to about 75° C. and kept at this temperature for about 10minutes. The resulting pigment composition had a water content of about35% by weight and a pigment content of about 10% by weight.

Working Instruction 1

Preparation of Carmine Composition Using Gum Arabic as Hydrocolloid

The composition is prepared using essentially the same method andingredients as described in Example 1 substituting 7.9 kg gelatin with10.5 kg gum arabic (dry weight) and reducing the amount of sugar to 11.6kg.

EXAMPLE 2

Preparation a Carmine Composition with Dispersion of Carmine in TwoSteps

1.0 kg of gelatin (dry weight) was added slowly to 16.0 kg demineralisedwater at a temperature of about 65° C. with agitation until the gelatinwas dissolved. 15.5 kg of sucrose was added under agitation until thesugar was dissolved. 10.5 kg of carmine was added to the above mixtureunder agitation using a mechanical stirrer. Mixing was continued until ahomogeneous mixture was obtained. The mixture was milled using asuitable mill until a stable dispersion of the pigment was obtained. Themilled product was heated under gentle agitation to about 70° C., 7.0 kgof gelatine was added and dissolved using agitation. The temperature waskept at this temperature for about 10 minutes. The resulting compositionhas a water content of about 32% by weight.

EXAMPLE 3

Preparation of a Norbixin Composition

A gelatin-sugar solution was prepared by slowly adding 2.0 kg gelatin(dry weight) to 4.4 kg of demineralised water at a temperature of about65° C. with agitation until the gelatin was dissolved. 3.6 kg sucrosewas added with agitation until the sugar was dissolved. 0.39 kg pigmentA-1400-WS (4.8% alkaline aqueous solution of annatto) was added to 9.6kg the above mixture under agitation using a mechanical stirrer. Mixingwas continued until a homogeneous mixture was obtained. The pH of themixture was about 5.6. The resulting composition has a water content ofabout 46% by weight.

EXAMPLE 4

Preparation of a Chlorophyllin Composition

100 g chlorophyllin powder was dissolved in 300 g demineralised waterand the pH of the solution was decreased to about 4-5 with 25 g citricacid. 150 g gelatin (dry weight and 425 g sucrose was added anddissolved by increasing the temperature of the medium to about 65° C.with agitation until a homogeneous mixture was obtained.

The mixture was milled until the required pigment size was obtained. Themilled product was heated under gentle agitation to about 75° C. andkept at this temperature for about 10 minutes. The resulting pigmentcomposition had a water content of about 30°% by weight.

EXAMPLE 5

Comparative Study of Migration in an Acidulated Dessert Coloured withPigment Composition According to the Invention and Reference ColouringAgents

Mashed apple was mixed with the below amount of colouring agents and 25ml glass containers were filled half with the mixtures, the remaininghalf of the containers were filled with yogurt. The container were keptat 5° C. and the migration of the colour into the yogurt layer in cm wasrecorded after 4, 7, 11 and 28 days.

The reference colouring agent was a product of Chr. Hansen A/S,Hørsholm, Denmark. The following agents were tested (dosages in gcolouring agent/g mashed apple):

CO-820-WS-AP: carmine acid dissolved in propylene glycol, citric acidand water (0.150)

Carmine composition of Example 1 (0.052),

TABLE 5.1 Migration of test compositions and reference colouring agentsin cm Days 4 7 11 Carmine, reference 1 1.8 1.8 Carmine, test 0 0 0

These results clearly shows that migration did not occur with thenatural pigment composition according to the invention, whereas thereference product containing the corresponding pigments in solutionmigrated to a significant extent.

EXAMPLE 6

Coating of Confectionary Using Coating Syrups Containing Natural PigmentCompositions

A coating syrup was prepared from 3.5 kg sucrose and 1.5 kg water bymixing and heating to 80° C. under agitation with a propel stirrer. Thesyrup was cooled to 50° C. and 270 g of a natural pigment compositionaccording to the invention containing about 5% of pigment was added tothe syrup.

A coloured coating syrup containing a pigment composition with carminewas prepared in this manner. The concentration of the natural pigment inthe syrup was about 0.4% of the syrup dry matter.

4-5 kg confectionary centers with a diameter of 17 mm and with a sugarcoating containing TiO₂ were used to test the colouring ability of thecoating syrup.

In the experiment, a satisfactory colour of the resulting dragees wasobtained even with 3-4 layers of coloured syrup and a strong and darkcolour was obtained after 10 layers of coating.

The experiment illustrated that the natural pigment compositiondispersed very well without the use of a-high speed mixer.

The colouring ability was high in that good colouring was seen afteronly 3-4 layers without the addition of gum arabic which is often usedin coating syrups to enhance the adherence of the colouring agent. Itwas observed that no colouring of teeth, mouth or hands occurred oneating the coloured dragees.

EXAMPLE 7

The Performance at Low pH of a Carmine Composition According to theInvention (Test-Carmine)

A problem which is encountered with known colouring agents containingcarmine lake is that they are not suitable for use in acid productssince the lake at low pH is dissociated into free carminic acid wherebythe colour hue changes from carmine red to orange red. Additionally, thelow pH generated degradation of the lake may include a precipitation ofthe chelated carminic acid.

The Test-Carmine product was therefore tested for possible acidstability by adding it to the soft drink medium as described below. Aconcentrated soft drink medium with the following composition wasinitially prepared:

Sucrose 430.0 g Na-benzoate, food grade 0.7 g K-sorbate, food grade 0.9g Ascorbic acid 0.1 g Citric acid monohydrate, food grade 8.6 gDemineralised water, ad 1000.0 g

Subsequently the concentrated medium was diluted 1:4 with demineralisedwater resulting in a soft drink medium having a pH of 3.0±0.2. 200 ppmpigment composition as prepared in Example 1 was added as test sample tothe diluted soft drink medium. As references were used equivalentpigment concentrations of the above colouring agent CO-820-WS-AP(Example 5) which contain carminic acid in propylene glycol and citricacid and CC-500-WS, an alkaline solution of carmine.

After addition of the Test-Carmine and the reference colouring agent,the colour hue of the soft drink with Test-Carmine was carmine red asdesired whereas the soft drink with the reference product CO-820-WS-APbecame orange and the reference product CC-500-WS precipitated. Noprecipitation of carminic acid was observed in the Test-Carmine sample.After 50 days, the carmine red colour hue was retained in the samplewith Test-Carmine.

It was also observed that the addition of the Test-Carmine compositionresulted in an attractive cloudiness (which is not due to precipitation)of the soft drink in contrast to the reference sample which remainedtransparent.

EXAMPLE 8

The Performance of Pigment Compositions in Soft Drink

10% by weight of pigment compositions of carmine and chlorophyllin asprepared in Examples 1 and 4, respectively (Test-Carmine andTest-Chlorophyllin) were added as test samples to the diluted soft drinkmedium as prepared in Example 7. The following colouring agentscontaining the corresponding pigments were added to the soft drinkmedium as reference samples:

CC-500-WS, 5% carmine in alkaline solution,

C-10,000-WS-AP, chlorophyllin in polysorbate and propylene glycol,

L*a*b* values were measured using a Minolta Tristimulus CT-210 equippedwith a D65 lamp in a 1 cm cuvette. The measurements were made afterdissolution/dispersing of the colours and after storage for 8 weeks inthe light and dark, respectively. ΔE expresses the difference in colourparameters. The results are summarized in the below table:

TABLE 8.1 Appearance of soft drink medium and colour parameters afterstorage and exposure to light Colour parameters Appearance Δ hue InitialAfter 1 week ΔE angle Test condition Test-Carmine Cloudy Cloudy 21Daylight 8 weeks CC-500-WS Trans- Precipitated 60 parent Test-Chloro-Cloudy Cloudy 2.8 2.6 1.5 hours in phyllin Suntester CPS C-10,000-WS-Trans- Cloudy/pre- 6.4 12.1 600 W/m², AP parent cipitated Xenon

These results illustrate that the compositions according to theinvention have a high stability as compared to the reference colouringagents. Furthermore, the water dispersible Compositions of the inventionconfer to the soft drink medium a cloudy appearance whereas thereference soft drink samples remained transparent. A cloudy appearanceof a soft drink is a highly desirable characteristic of a coloured softdrink.

EXAMPLE 9

The Performance at Low pH of Norbixin Composition According to theInvention (Test-Norbixin)

About 1 ml of the norbixin composition obtained in Example 3 and areference A-320-WS (1.1% alkaline aqueous solution of annatto) wereadded to 100 ml demineralised water and the above soft drink medium,respectively. The following was observed:

TABLE 9.1 Performance of norbixin composition in soft drink anddemineralised water Demineralised water Soft drink medium Test-NorbixinCloudy Clear yellow/orange solution A-320-WS Clear orange/yellowPrecipitation solution

The four samples were stored at room temperature in a dark place for 15month. The reference sample was unchanged in the soft drink solutionwhereas the colour had disappeared from the reference sample indemineralised water. The Test-Norbixin was unchanged both in the softdrink medium and in the demineralised water sample.

The above shows that with the compositions of the present invention itis also possible to obtain transparent solutions at acidic pH and thatthey are stable in acidic media.

EXAMPLE 10

The Performance of Chlorophyllin in Soft Drink Concentrate

200 ppm chlorophyllin composition as prepared in Example 4 was used ascolouring agent in the concentrated soft drink medium described inExample 7. A reference sample was coloured using the above describedcolour C-10,000-WS-AP in the same chlorophyllin concentration.

The following results were obtained after 1 and 4 weeks of storage:

TABLE 10.1 Appearance of concentrated soft drink medium Colouring agent1 week 4 weeks Test-Chlorophyllin No ring formation No ring formationC-10,000-WS-AP Ring formation Ring formation

The above results show that with regard to ring formation thecompositions according to the invention are superior to the equivalentwater-soluble composition.

What is claimed is:
 1. A ready-to-use water dispersible pigment composition that contains in excess of 10% by weight of water, the composition comprising a dispersion of a water-insoluble hydrophilic natural pigment in the form of bodies of an average size which is at the most 10 μm, said bodies being dispersed in the absence of a surface active substance in an aqueous phase comprising a hydrocolloid, the composition, when it is added to a food product or a pharmaceutical product comprising multiple, separated compartments, whereby the composition is dispersed in one or more selected compartments, essentially does not migrate from said compartment(s) where it is dispersed into other compartments.
 2. A composition according to claim 1 wherein the natural pigment is a pigment that is generally insoluble in aqueous media at about neutral pH or below but soluble in aqueous media at pH values in the alkaline range.
 3. A composition according to claim 2 wherein the pigment is selected from the group consisting of a porphyrin pigment, carmine, curcumin and a carotenoid.
 4. A composition according to claim 3 wherein the pigment is in the form of particles obtained by precipitation of the pigment caused by acidifying an alkaline solution of the pigment.
 5. A composition according to claim 1 wherein the aqueous phase comprises a carbohydrate.
 6. A composition according to claim 1 wherein the hydrocolloid is selected from a protein, a polysaccharide and a gum.
 7. An edible product comprising a composition according to claim
 1. 8. An edible product according to claim 7, comprising multiple, separated compartments such that the composition is dispersed in one or more selected compartments, and the composition in one compartment essentially not migrating to other compartments.
 9. A pharmaceutical product comprising a composition according to claim
 1. 10. A pharmaceutical product according to claim 9, comprising multiple, separated compartments such that the composition is dispersed in one or more selected compartments, and the composition in one compartment essentially not migrating to other compartments.
 11. A method of preparing a ready-to-use water dispersible pigment composition according to claim 1, said method comprising preparing a dispersion of a water-insoluble, hydrophilic natural pigment by mixing the pigment in the absence of a surface active substance into an aqueous phase containing a hydrocolloid, to obtain a dispersion comprising the pigment in the form of bodies having an average size of at the most 10 μm, the composition containing at least 10% by weight water.
 12. A method according to claim 11, which comprises the further step of drying the dispersion to obtain a composition containing less than 5% by weight of water, subject to the limitation that, when the pigment is carmine or spray-dried norbixin, the hydrocolloid is not gelatin.
 13. A method according to claim 11 wherein the solid pigment is in the form of particles obtained by precipitation of the pigment caused by acidifying an alkaline solution of the pigment.
 14. A method according to claim 11 wherein the amount of hydrocolloid is less than 10% by weight calculated on the pigment.
 15. A method according to claim 11 which comprises a further step wherein an additional amount of hydrocolloid is added.
 16. A method according to claim 11 wherein a carbohydrate is added to the aqueous phase.
 17. A ready-to-use water dispersible pigment composition comprising a dispersion of a water-insoluble, hydrophilic natural pigment in the form of bodies of an average size which is at the most 10 μm, said bodies being dispersed in the absence of a surface active substance in an aqueous phase comprising a hydrocolloid, the composition containing less than 5% by weight of water, subject to the limitation that when the pigment is carmine or spray dried norbixin the hydrocolloid is not gelatin, said composition, when it is added to a food product or a pharmaceutical product comprising multiple, separated compartments, whereby the composition is dispersed in one or more selected compartments, essentially does not migrate from said compartment(s) where it is dispersed into other compartments.
 18. A composition according to claim 17 wherein the composition is dispersed in an aqueous phase of said edible food product.
 19. A composition according to claim 17 wherein said composition is a pharmaceutical product.
 20. A ready-to-use water-dispersible composition comprising a dispersion of a hydrophilic natural pigment in the form of bodies of an average size which is at the most 10 μm, said bodies being dispersed in the absence of a surface active substance in an aqueous phase comprising a hydrocolloid, the composition containing in excess of 10% by weight of water, in the manufacturing of an edible product whereby the composition is dispersed in an aqueous phase of said edible food product.
 21. A composition according to claim 20 wherein the aqueous phase has a pH which is at the most
 7. 22. A ready-to-use water-dispersible composition comprising a dispersion of a hydrophilic natural pigment in the form of bodies of an average size which is at the most 10 μm, said bodies being dispersed in the absence of a surface active substance in an aqueous phase comprising a hydrocolloid, the composition containing in excess of 10% by weight of water, in the manufacturing of a pharmaceutical product.
 23. A method of preparing a ready-to-use water dispersible pigment composition, said method comprising the steps of: i) preparing an alkaline aqueous solution comprising a water-insoluble, hydrophilic natural pigment, ii) preparing an aqueous dispersion or solution of a hydrocolloid, iii) mixing the alkaline aqueous solution with the aqueous dispersion or solution of a hydrocolloid and iv) if desired, adjusting the pH to a level which causes the pigment to precipitate, to obtain the composition comprising the pigment in the form of a dispersion of pigment bodies having an average size of at the most 10 μm, the composition containing at least 10% by weight water.
 24. A method according to claim 23, which comprises the further step of drying the composition of pigment bodies to obtain a composition containing less than 5% by weight of water, subject to the limitation that, when the pigment is carmine or spray-dried norbixin, the hydrocolloid is not gelatin.
 25. A method according to claim 23 wherein the aqueous solution of step i) and/or the dispersion or solution of step ii) comprises a carbohydrate.
 26. A method of preparing a ready-to-use water dispersible pigment composition, said method comprising the steps of: i) preparing an alkaline aqueous solution comprising a water-insoluble, hydrophilic natural pigment followed by decreasing the pH to a level which causes the pigment to precipitate, resulting in a dispersion of precipitated pigment, ii) preparing an aqueous dispersion or solution of a hydrocolloid, iii) mixing the dispersion comprising the precipitated pigment of step i) and the dispersion or solution of a hydrocolloid of step ii), to obtain the composition comprising the pigment in the form of a dispersion of pigment bodies having an average size of at the most 10 μm, the composition containing at least 10% by weight water.
 27. A method according to claim 26, which comprises the further step of drying the composition of pigment bodies to obtain a composition containing less than 5% by weight of water, subject to the limitation that, when the pigment is carmine or spray-dried norbixin, the hydrocolloid is not gelatin.
 28. A method according to claim 26 wherein the dispersion comprising the precipitated pigment of step i) and the dispersion or solution of step ii) comprises a carbohydrate. 